The present invention relates to a fuel pipe.
Japanese Examined Utility Model Publication No. 6-29496 describes a fuel pipe that distributes and supplies fuel fed by a fuel pump to a plurality of fuel injection valves. The fuel pipe includes a cylindrical header pipe. The header pipe includes a fuel inlet through which the fuel fed from the fuel pump is drawn and a plurality of fuel outlets through which the fuel is supplied from the header pipe to the fuel injection valves. The fuel outlets are arranged next to each other in the axial direction of the header pipe. The bases of the fuel injection valves are fitted into corresponding fuel outlets in a liquid-tight manner. When the fuel is injected from the fuel injection valves, fuel is supplied from the header pipe to the fuel injection valves through the fuel outlets.
The fuel pipe may be constructed by molding the header pipe separately from the fuel outlets and then coupling the fuel outlets to the header pipe. In such a construction, the header pipe includes a communication hole at a joining portion where each fuel outlet is connected to the header pipe. A flow passage extending through the fuel pipe has a cross-sectional area that is smaller at portions where the fuel outlets are located than other portions. Thus, in a situation immediately after the injection of fuel from each fuel injection valve, the flow rate of fuel is restricted at the communication hole. This momentarily causes the fuel pressure at the fuel outlet side to which the fuel injection valve is connected to be lower than the fuel pressure at the header pipe side. Such a difference in fuel pressure may vibrate the fuel pipe. It is desirable that the difference in fuel pressure be reduced by increasing the area of the communication hole while properly maintaining the required coupling strength between the header pipe and the fuel outlet. However, the above publication does not describe such matter thereby leaving room for improvement.